Electrical discharge apparatus



Oct. 29, 1940. B. BERGHAUS ET AL ELECTRICAL DISCHARGE APPARATUS FildMarch 20, 1959 Biw- Patented Oct. 29, 1940 UNITED STATES PATENT OFFICEELECTRICAL DISCHARGE APPARATUS Application March 20, 1939, Serial No.263,076 In Germany March 24, 1938 4 Claims.

The invention relates to a lead-in conductor for vacuum, reactionapparatus, the characteristic feature of which is that the insulatingmaterial is protected by a gap against any attack 5 by the gasdischarge.

The invention also relates to a lead-in conductor for electric vacuumreaction apparatus, the characteristic feature of which is that theinsulated cathode conductor, to which the required voltage is appliedfor the chemical reaction by means of an electric discharge at reducedpressure, is provided with a metal covering at a short distance,preferably projecting into the vacuum reaction chamber. The insulatingand sealing material of the conductor is so arranged that it is notreached by the charge carriers and metal vapour present in the vacuumreaction chamber. The distance between the conductor and the metalcovering is made smaller than the width of the glow fringe which isformed around the con ductor and the electrodes, more particularly, thecathode. The distance of the metal covering from the conductor dependsupon the nature of the gas, the pressure and temperature of the gasbeing about 0.1 to 20, preferably 0.5 to 5 millimeters, and the metalcovering has such a length that the glow and the charge carriers fromthe ionised atmosphere of the furnace, as Well as the metal vapour, donot reach the insulating and the sealing material. The length of theprotective gap is preferably a multiple of its width. The insulatedmetal covering may lie in the ionised gas space without any directelectric conr nection and carry a positive potential. Further, it may bein electric contact with the casing of the vacuum, reaction chamber andbe even earthed. The metal covering of the lead-in conductor may also beinsulated with respect to the casing, in addition to being insulatedfrom the conductor and carry a different voltage than the casing or theconductor. The screen of the conductor is preferably so shaped as toavoid as much as possible the presence of edges and points.

The insulation and sealing of the conductor is preferably providedoutside the vacuum reaction chamber so that they are easily accessible.The conductor may be constructed asa round hollow member, the inner wallof which is capable of being cooled by a cooling means, such as air,oil, or water.

A further feature of the invention resides in the fact that theconductor is surrounded by a .lurality of concentric metal coverings,which are arranged in an insulated manner and at a short distance withrespect to one another and to the conductor. The metal coverings maycarry different voltages with respect to one another and the conductor.In order to regulate the distribution of the voltage on the metalcoverings use is preferably made of condensers or resist- 5 ances. Theflange oi the screening sleeves may be made so as to be capable of beingcooled, in order to protect the insulator.

The invention has the advantage that, owing to the gradation of thevoltage between the individual metal coverings, high voltages can bereliably introduced in the vacuum reaction chamber in the case of largepowers. The device offers a special advantage when the lead-in conductoris used in metallic reaction chambers wherein the high voltage isapplied between the wall of the chamber and the conductor. Both theconductor and the wall of the chamber may carry the negative voltage.The same advantages are obtained with the lead-in conductor when thedirection of the current is continuously varied, as is, for instance,the case when an alternating current voltage is applied. By using alead-in conductor such as described it was possible to apply voltages upto 16,000 volts and more, and over 125 100 kilowatts, without in any waydamaging or destroying the insulating part, even with a long period ofoperation.

The present invention avoids the difilculties hitherto encountered withlead-in conductors 0W- 0 ing to the undesirable glow and are dischargesat the point where the lead-in conductors enter into the vessel, whichwould otherwise lead to the destruction ofthe sealing and insulatingmaterial. The lead-in conductor allows powers of 100 kw. for voltages ofa few thousand volts to be reliably supplied to vacuum apparatus of anydesired construction in which the Wall of the vessel forms permanentlyor temporarily the cathode. A direct or alternating current voltage maybe applied to the lead-in conductor.

The invention is illustrated by way of example and diagrammatically inthe accompanying drawing, in which- Fig. l is a sectional elevation ofvacuum reaction apparatus in which the wall is connected as the cathodeof a glow discharge with respect to an anode introduced in an insulatedand screened manner.

Fig. 2 is a sectional View of a lead-in conductor showing another formof screen for vacuum reaction apparatus.

Fig. 3 is a sectional View of the lead-in conductor showing a modifiedscreen assembly and electrical connections therefor.

Referring to Fig. 1, which is a sectional elevation of a vacuumapparatus for car-rying out chemical reactions in which the wall of theapparatus serves as a cathode, 35s is the reaction vessel which isclosed in an airtight manner by a lid 95 through the interposition of apacking 96. The whole interior of the reaction apparatus, that is tosay, the lid as well as the vessel, is coated with a suitable electrodematerial 97, which may consist of any desired metal, a metal alloy orametalloid. The following metals may be used, copper, iron, aluminium,light metals and the like. The vacuum pump, which is not shown, isconnected up to the pipe connection 98 in the lid, whilst the pipeconnection 99 serves for the purpose of supplying the component parts ofthe reaction. The reaction vessel is surrounded by a jacket 560 to whicha cooling medium, for instance water, oil or air, is supplied throughthe pipe connection iGl. The cooling medium is discharged through thepipe connection l02. The lid is secured to the vessel by clamps I03 andmay be conductively connected to the vessel by the removable conductorlt i. The negative voltage is supplied by the cable Hi which is securedto the lid. When use is made of catalysts I06, these are suspended, forinstance, from a frame lll'l, which is secured to the insulated andscreened lead-in conductor E08, and may be connected by the cable is tothe negative pole of a source ofdirect current voltage. The connectionof the catalysts to the source of direct current may also beinterrupted, so that the catalysts are then suspended in the reactionvessel neutral. l H], H i and H2 are rings of insulating and packingmaterial and H3 is the metallic screening sleeve, the hollow flange iiiof which is adapted to be cooled by a cooling medium, and

which is clamped on to the lid by means of screws which, for the sake ofclearness, have not been illustrated. The positive voltage is applied tothe screening sleeve by the cable H6. The screening sleeve may carry atits end an anode III which is for instance in the form of a plate.Between the anode li'i and the wall 91 of the reaction vessel, which isconnected as a cathode, there is then produced a gas discharge at apressure between 40 and 0.001 and preferably between 5 and 0.1millimeters of mercury, for carrying out the chemical reaction.

Also the lid of the vessel is provided with a jacket H8, to which thecooling medium is supplied by the pipe connection 5 39 being dischargedthrough the pipe connection I 20.

According to the invention a filter 99a is builtin the gas supply 99 anda filter 98a in the gas discharge 98, which prevents the gas discharge,more particularly the glow discharge, from striking into the gas supplyor discharge pipe. The mesh of the sieve is, for instance, less than 1mm. Liquid reaction products which may be formed are discharged throughthe pipe connection m.

The lead-in conductors hereinbefore described are suitable for directcurrent as well as for alternating current such as multi-phase currents,for instance three phase currents.

The form of construction illustrated in Fig. 2 includes a metallicscreening sleeve 3i surrounding the lead-in conductor and constructed asa hollow body capable of being cooled, to which the cooling medium issupplied through the pipe 32- and discharged through the pipe 33. 34 isan insulating member and 35 is the clamping ring of insulating material,while 36 is a packing ring.

Referring to the-form of construction illustrated in Fig. 3, 2 is themetallic wall of the vacuum chamber into which the conductor 3 isintroduced through a hole in the wall. The conductor is for instancemade hollow and cooled by a cooling medium, such as water, oil or air.The cooling medium is introduced through the pipe 4 and is dischargedthrough the pipe. 5. The conductor 3 is surrounded by a plurality, forinstance four, cylindrical metal sleeves 6a, 6b, 6c, 612, which areprovided at one end with a flange, while at the other end they projectinto the reaction chamber to such an extent that no discharges or metalparticles can reach from the reaction space through the narrow annularspaces between the conductor 3 and the sleeve 6a, as well as between theother sleeves to the insulation and packings which are arranged outsidethe vacuum chamber. la, lb, lo and 1d are rings used for insulatingpurposes. The flange 10 of the conductor 3 is firmly clamped by means ofa ring I i of insulating material and screws I2. I4 is a lead throughwhich current is supplied to the conductor 3. 59, 60, 6|, 62 areresistances. 63, 6 4, 65, 66 are condensers for regulating the voltageon the screening sleeves. By means of the lead-in conductor hereinbeforedescribed voltages up to 10,000 vol-ts can be applied without destroyingthe insulation, even in the case of high temperatures in the vacuumreaction apparatus.

What we claim is:

1. In electric vacuum reaction apparatus adapted to support a gasdischarge therein, a metallic housing having an opening therein, ahollow conduct-or extending into the housing through said opening, ascreening sleeve extending into the housing through said opening andsurrounding said conductor in such a spaced relation that the gasdischarge cannot extend outside the housing through said space, andmeans arranged outside the housing for sealing and insulating saidconductor with respect to the housmg.

2. In electric vacuum reaction apparatus adapted to support a gasdischarge therein, a metallic housing having an opening therein, ahollow conductor extending into the housing through said opening, ascreening sleeve extending into the housing through said opening andsurrounding said conductor in such a spaced relation that the gasdischarge cannot extend outside the housing through said space, meansarranged outside the housing for sealing and insulating said conductorwith respect to the housing, and means for introducing a cooling mediuminto said conductor.

3. In electric vacuum reaction apparatus adapted to support a gasdischarge therein, a metallic housing having an opening in the wallthereof, a hollow conductor extending into the housing through saidopening, a hollow screening sleeve extending into said housing throughsaid opening and surrounding said conductor in such a spaced relationthat the gas discharge cannot extend outside the housing through saidspace, means arranged outside the housing for sealing and insulatingsaid conductor with respect to the housing,'and means for introducing acooling medium into said hollow screening sleeve.

4. In electric vacuum reaction apparatus adapted to support a gasdischarge therein, a metallic housing having an opening in the wallthereof, a hollow conductor extending into said housing through saidopening, a plurality of concentrically arranged screening sleevesextending into said housing through said opening, said sleeves beingspaced with respect to each other and the innermost sleeve being spacedwith respect to said conductor so that the gas discharge cannot extendoutside said housing through said spaces, means arranged outside saidhousing for insulating and sealing said conductor with respect to theinnermost sleeve, means arranged outside said housing insulating andsealing said sleeve with respect to each other, and means arrangedoutside the housing for sealing the outermost sleeve with respect to thehousing.

BERNHARD BERGHAUS. WHJHELM BURKHARDT.

